perf/ftrace: Optimize perf/tracepoint interaction for single events

When we've got but a single event per tracepoint
there is no reason to try and multiplex it so don't.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 0565bb42566f..89b780a7c522 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -27,13 +27,15 @@ typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
 /* Count the events in use (per event id, not per instance) */
 static int      total_ref_count;
 
-static int perf_trace_event_enable(struct ftrace_event_call *event)
+static int perf_trace_event_enable(struct ftrace_event_call *event, void *data)
 {
         char *buf;
         int ret = -ENOMEM;
 
-        if (event->perf_refcount++ > 0)
+        if (event->perf_refcount++ > 0) {
+                event->perf_data = NULL;
                 return 0;
+        }
 
         if (!total_ref_count) {
                 buf = (char *)alloc_percpu(perf_trace_t);
@@ -51,6 +53,7 @@ static int perf_trace_event_enable(struct ftrace_event_call *event)
 
         ret = event->perf_event_enable(event);
         if (!ret) {
+                event->perf_data = data;
                 total_ref_count++;
                 return 0;
         }
@@ -68,7 +71,7 @@ fail_buf:
         return ret;
 }
 
-int perf_trace_enable(int event_id)
+int perf_trace_enable(int event_id, void *data)
 {
         struct ftrace_event_call *event;
         int ret = -EINVAL;
@@ -77,7 +80,7 @@ int perf_trace_enable(int event_id)
         list_for_each_entry(event, &ftrace_events, list) {
                 if (event->id == event_id && event->perf_event_enable &&
                     try_module_get(event->mod)) {
-                        ret = perf_trace_event_enable(event);
+                        ret = perf_trace_event_enable(event, data);
                         break;
                 }
         }